Septic shock is dominated clinically by circulatory changes presenting with profound vasodilatation and hypotension. Cardiac output values are often seemingly normal, or even enhanced, when compared with the physiological range. However, relative to the vasodilatation, cardiac output is often not adequately enhanced. Thus, the degree of myocardial depression in sepsis is often underestimated by the clinician, albeit a factor that markedly increases mortality.